Rats at 10,000 ft? Amazing! I have lived in my town since 1969 and have never seen a rat, either dead or alive. One of my kids is a pest control operator and he has never found/killed one here either.
I have also spoken with other people in town that have had different equipment stored outdoors over the past 30 years, and they have never had a problem with rats or any other critter chewing wires.
It will be interesting to see what my client says. As I mentioned before, there was absolutely no evidence of any nesting, or pieces of the woven loom on the ground, or anywhere else for that matter. It has to be chaffing, or something along those lines.
Tim